Diseases Carried by Ticks

Rocky Mountain Spotted Fever

Rocky Mountain spotted fever is a serious, generalized infection that is usually spread to
people by the bite of infected ticks carrying the bacterial organism Rickettsia rickettsii. The
disease gets its name from the Rocky Mountain area where it was first identified. Rocky Mountain
spotted fever is found throughout the continental United States. Despite the name, most disease
cases occur in the southeastern United States. Rocky Mountain spotted fever is spread by the
American dog tick, the lone-star tick, and the wood tick, all of which like to live in wooded areas
and tall, grassy fields. The disease is most common in the spring and summer when these ticks are
active, but it can occur anytime during the year when the weather is warm. Rocky Mountain spotted
fever is not spread from person to person, except rarely by blood transfusion. Symptoms usually
begin 3 to 12 days after a tick bite. Without prompt medical care, kidney failure and shock can
lead to death. Rocky Mountain spotted fever must be treated with antibiotics. Many persons with the
disease need to be hospitalized.

Colorado Tick Fever

The disease is limited to the western U.S. and is most prevalent during March to August during
the tick season. The incubation period is 3 to 6 days. Symptoms of fever continue for 3 days, then
abate and recur 1 to 3 days later for another few days. Risk factors are recent outdoor activity
and recent tick bite. The incidence is 4 out of 100,000 people.

Tularemia or "rabbit fever"

Tularemia is a disease caused by the bacterium Francisella tularensis. Tularemia is typically
found in animals, especially rodents, rabbits, and hares and has been reported in all U.S. states
except Hawaii. People typically become infected through the bite of a tick or other biting insect.
Possible symptoms include skin ulcers, swollen and painful lymph glands, inflamed eyes, sore
throat, mouth sores, diarrhea or pneumonia. Tularemia can be fatal if the person is not treated
with appropriate antibiotics. About 200 human cases of tularemia are reported each year in the
United States. Most cases occur in the south-central and western states. Nearly all cases occur in
rural areas, and are caused by the bites of ticks and biting flies or from handling infected
rodents, rabbits, or hares.